@unpublished{upm47960,
            year = {1908},
          author = {Francisco Bertr{\'a}n Musitu},
           title = {Explotaci{\'o}n de un fil{\'o}n de galena y blenda argent{\'i}feras},
        abstract = {Explotaci{\'o}n de un fil{\'o}n de galena y blenda argent{\'i}feras},
             url = {https://oa.upm.es/47960/}
}